Al₂O₃ ceramic and multi-system metal integrated brazing structure optimization and sealing reliability

The integrated brazing structure of an electrical connector consisting of 0Cr18Ni9 stainless steel shell, Al₂O₃ insulating ceramic and Kovar central electrode was optimized by finite element calculations. On this basis, Ag-5Cu-1Al-1.25Ti brazing alloy was used to realize one-step sealing of the component at 930 ℃/30 min. The microstructure of the joints and the service reliability of the component were analyzed. The results indicate that the residual stress of the ceramic matrix can be significantly reduced by improving the welding position and brazing alloy addition form. During the brazing process, the active element Ti accumulated towards the ceramic side and reacted. Ti₃(Cu, Al)₃O reactive layer was formed on the Al₂O₃ ceramic side; the reaction products on the stainless steel side were TiFe₂ and Fe-Cr intermetallic compounds; while the Kovar base material dissolves into the liquid brazing alloy and reactes with Ti to form Ti₂Ni and TiFe₂. The leakage rate of the composite component is less than 7.0 × 10⁻¹² Pa·m³/s after the thermal cycles, verifying its reliability under extreme conditions. The research findings can provide simulation data support and theoretical guidance for the design of electrical connectors under extreme temperature change conditions.